[Release of fluoride by fluoridated amalgams and its incorporation by dental enamel]

Liberation of stannous fluoride incorporated in the alloy powder before amalgamation was demonstrated for all the amalgams tested in this study. This liberation was observed for stannous fluoride concentrations of 0.5% and 1%. Clear differences were noted in relation to the type of amalgam studied. Through the use of a non destructive method (activation with charged particles) it was possible to measure the fluoride concentration in enamel before and after the contact with the fluoridated amalgam. This analysis demonstrated that the fluoride liberated from the amalgam was trapped by enamel in contact with alloys containing 0.5% or 1% of stannous fluoride. The enrichment in fluoride was very important in the first weeks and remained high after four months. No significant difference appeared between alloys fluoridated at 0.5% and 1%. The dissolution of calcium fluoride through a KOH treatment showed that the amount of stable fluoride (fluorapatite) formed was important.